1. Field of the Invention
The present invention relates to an intrusion detection system that has a pair of leaky transmission paths including a leaky transmission path of a sending side which is connected to an intrusion detection device and outputs a leaky electric wave on the basis of an output from the intrusion detection device and a leaky transmission path of a receiving side which receives the leaky electric wave output from the leaky transmission path of the sending side, and that performs intrusion detection by the intrusion detection device which detects variation of the leaky electric wave received in the leaky transmission path of the receiving side.
2. Description of the Related Art
An intrusion detection system that has a pair of leaky transmission paths including a leaky transmission path of a sending side which is connected to an intrusion detection device and outputs a leaky electric wave on the basis of an output from the intrusion detection device and a leaky transmission path of a receiving side which receives the leaky electric wave output from the leaky transmission path of the sending side, and that performs intrusion detection by the intrusion detection device which detects variation of the leaky electric wave received in the leaky transmission path of the receiving side is a relatively recent technology, as shown in, e.g., US-2007-0152817-A1 (corresponding to JP-A-2007-179402), US-2007-0152818-A1 (corresponding to JP-A-2007-179401), JP-A-2007-189521, and U.S. patent application Ser. No. 11/907,053 (not laid open into public as of Mar. 17, 2008). Accordingly, the practical use of the technology also began relatively recently. Since the system is used to detect intrusion of a person entering a factory or a runway of an airport, for example, and is not installed around electric equipment causing noise, measures for noise caused by other electric equipment are not necessary, in general. Accordingly, the measures for noise are not made.
As described above, the intrusion detection system that has the pair of leaky transmission paths including the leaky transmission path of the sending side which is connected to the intrusion detection device and outputs the leaky electric wave on the basis of the output from the intrusion detection device and the leaky transmission path of the receiving side which receives the leaky electric wave output from the leaky transmission path of the sending side, and that performs the intrusion detection by the intrusion detection device which detects the variation of the leaky electric wave received in the leaky transmission path of the receiving side is used to detect the intrusion of a person entering a factory or a runway of an airport, for example, and is not installed around the electric equipment causing noise, and thus the measures for noise caused by other electric equipment are not necessary, in general. Accordingly, the measures for noise are not made. However, when the detection of the intrusion of a person is a target, it is necessary to assume that an intruder having highly-specialized experience intrudes. In such case, when the intruder intrudes while emitting a disturbing wave similar to a leaky electric wave received in the leaky transmission path of the receiving side, the intrusion detection device which detects the variation of the leaky electric wave received in the leaky transmission path of the receiving side may malfunction.